Interfacial band bending induced charge-transfer regulation over Ag@ZIF-8@g-C3N4 to boost photocatalytic CO2 reduction into syngas

Abstract

Ternary Ag@ZIF-8@g-C₃N₄ was successfully constructed via a facile method. The doped Ag component simultaneously serves as a charge-transfer switcher, electron–hole mediator, and co-catalyst in this system. The Ag@ZIF-8@g-C₃N₄ heterostructure could support a high redox potential to drive the photoreduction of CO₂ and MB photodegradation under visible light excitation. The M-S and UPS results indicated that a work-function regulation process was designed and engineered, and the Z-scheme charge-transfer pathway was more beneficial for enhanced CO₂ reduction and MB degradation. Ag@ZIF-8@g-C₃N₄-10 (named AZC-10) showed a stable and drastic increase in electron consumption during CO₂ reduction to syngas, approximately 158.05-, 3.45- and 2.1-times higher than the values for ZIF-8(Zn), g-C₃N₄, and ZIF-8@g-C₃N₄ (ZC), respectively. The dynamic kinetics of MB degradation were improved 9.4-fold compared to g-C₃N₄ (based on the rate constant). Based on the experimental results and characterization data, interfacial band bending was shown to induce charge-transfer switching, and a rational mechanism was proposed.